Skip to main content
Go to homepage

Print Page

Blood Test: von Willebrand Factor (vWF) Activity - Ristocetin Cofactor

What Is a Blood Test?

By taking and testing a small sample of a person’s blood, doctors can check for many kinds of diseases and conditions. Blood tests help doctors check how the body’s organs are working and see if medical treatments are helpful.

To help your child get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is anxious about it, work together on ways to stay calm.

What Is a vWF Activity – Ristocetin Cofactor Test?

Proteins called clotting factors help blood clot properly and help prevent too much bleeding. A von Willebrand factor (vWF) activity – ristocetin (riss-teh-SEE-tin) cofactor test lets doctors see how a protein called von Willebrand factor is working.

The body's clotting factors work together in a special order, almost like pieces of a puzzle. When the last piece is in place, the clot develops. But if there aren't enough of them, or any of them don't work as they should, it can take longer than normal for blood to clot.

Von Willebrand factor is involved in a few stages of blood clotting. An abnormal gene can make some kids not have enough vWF, or a defective version of it, causing the bleeding disorder von Willebrand disease.

Why Are vWF Activity – Ristocetin Cofactor Tests Done?

Doctors order the vWF activity – ristocetin cofactor test (also called von Willebrand activity test or RCF activity test) to help diagnose or monitor the treatment of von Willebrand disease. 

Often, doctors do this test along with others to get a fuller picture of clotting ability. These can include:

What if I Have Questions?

If you have questions about the vWF activity – ristocetin cofactor test or what the test results mean, talk to your doctor.

Reviewed by: Larissa Hirsch, MD
Date Reviewed: 01-09-2021

Lea este articulo en Español

What next?

Summit Mall Play Area
Answer Key:
Click to expand
There are 10 nurses in the picture.

And we have many more pediatric primary care providers in Northeast Ohio. You can meet some of them here.
Summit Mall Play Area
Answer Key:
Click to expand
The five differences are:
– Phone color
– Coat pocket
– Stethoscope earpiece color
– Stethoscope bell dot
– Clipboard paper color

Need help finding a doctor, choosing a location or getting a general question about Akron Children's answered? Call us or fill out the form and we'll help in any way we can.
Summit Mall Play Area
Answer Key:
Click to expand
The two matching doctors are 9 and 14.

With virtual visits, you can see our pediatric experts from the comfort of home or wherever you are.
Summit Mall Play Area
Answer Key:
Click to expand
The correct path:
The Correct Path
We offer many ways to get pediatric care all over Northeast Ohio. Use this page to find the right kind of care and the most convenient location for you.